Locks having a low co-efficient of thermal conductivity have been previously known as evidenced by the U.S. patent to Ryder U.S. Pat. No. 3,465,557 issued Sept. 9, 1969, and means for ejecting keys as an integral part of the lock have been disclosed in U.S. patents such as the patent to Erickson U.S. Pat. No. 3,748,881 issued July 31, 1973. While each of these locks function in a satisfactory manner, there were deficiencies in them, to the extent that they were expensive, had a multiplicity of parts and occasionally the metallic elements in the form of springs and tumbler members became affected by the thermal differential environment in which they were located.